The aim of this study was to verify the percentage of recirculation (%R) in patients on hemodialysis in different models of insertion of needles in arteriovenous fistula. Urea concentration was measured in samples of the arterial (A), venous line (V) and blood from the apposite arm (S) 10 minutes later in 8 patients using the classical model (apposite-oriented, 3 5 cm apart needles) as well as in patients with three other different models (8 patients in each group). The percentage of recirculation was calculated according to the formula %R= (S-A) / (S-V).100 . A significant lower percentage of recirculation occurred in the use of the classical model.